Abdominal ectopic pregnancy with undetectable serum β-human chorionic gonadotropin 9 days following blastocyst transfer.

With the availability of the highly sensitive β-human chorionic gonadotropin (β-hCG) assays, all pregnancies, including ectopic pregnancies (EP), are expected to have detectable serum β-hCG at 4 weeks' gestation or 9 days following blastocyst transfer. To our knowledge, this is the first report of a woman who underwent in vitro fertilization, had undetectable serum β-hCG 9 days after blastocyst transfer, and was then diagnosed with a ruptured abdominal EP and intra-abdominal bleeding 19 days later. This case highlights that the rise in serum β-hCG might be delayed in abdominal EP compared to intrauterine pregnancy. This delay should raise the suspicion for EP, thus meriting close monitoring. Moreover, in the absence of menstruation, an undetectable serum β-hCG 9 days post-blastocyst transfer should prompt β-hCG measurement in 2-3 days to avoid the misdiagnosis of an EP.